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Lessons from White-Space-Device Deployment in Virginia

Experimental station WF2XCG is "on the air" using high VHF TV spectrum in Claudville, Va. The application and authorization both show 168.000 to 216.000 MHz as the frequencies used, but I suspect the lower frequency should have been 186.000 MHz as 168.000 MHz is outside the TV band. The experimental license was granted to Spectrum Bridge, who also provided equipment for the test. Maximum TPO is 2 watts and ERP is limited to 2 watts. The units use OFDM modulation and FSK. The emission type is listed as 5M00F1D. All sites are fixed – no mobile wireless.

In its application, Spectrum Bridge said, "The Commission has indicated it expects the availability of white space spectrum will promote the development and deployment of innovative new services. Spectrum Bridge believe[s] that its research efforts will further these goals by facilitating techniques to test the extent of over-the-air television contours and to promote interference-free operations in white spaces.

Spectrum Bridge has information on the Claudville, VA test on its Web site [PDF]. An article late last week on, TV white-spaces network launched in rural Virginia has more technical details on the testing. In the article, Rick Rotondo, vice president of marketing for Spectrum Bridge, describes a case of TV interference. "Claudville is mountainous, and the signal from that TV transmitter was stronger than expected. It wasn’t strong enough to actually be received and be decoded by TVs there — we asked folks, and they could never get that channel—but it was enough that it caused a noise floor, so we just moved to a different channel."

This looks exactly like the type of white space use that MSTV and NAB support. The system is being used to provide "middle mile" connections between the computer lab and WiFi hot spots installed at the local school, in the cafe located in the business district, and small office/home office business users in the community. Dell and Microsoft donated computer equipment, Internet video systems and software to the school for the project.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.